ばこそ

ばこそ means "precisely because": it is this reason, and no other, that explains what follows. It is the ば-form with こそ on the end – おもえば思えばこそ, きびしければ厳しければこそ, おや親であればこそ – and despite the ば it is not an "if". The reason is a fact.

A noun or a な-adjective takes であれば, or なれば in older writing – never だれば.

• × 好きだればこそ → 好きであればこそ

The speaker is usually defending something that could be taken badly – a scolding, a refusal – and the sentence often ends in のだ or のです.

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ばこそ is literary. You meet it in essays, speeches and formal letters. In speech, and in most writing, say からこそ, which means the same and follows the plain form.

Older texts put it on a past verb as したればこそ: どりょく努力したればこそ, "precisely because I made the effort". Read it, but don't copy it.